Abstract
Chemical size effect on structural and magnetic properties in (Ca <sub>2-2x</sub> Sr <sub>2x</sub> )FeMoO <sub>6</sub> has been examined. The compounds crystallize in the monoclinic system for 0.0≤x<0.2, the orthorhombic for 0.2≤x<0.4 and the tetragonal for 0.4≤v. The Curie temperature T <sub>C</sub> increases with increasing x from 318 K (x = 0.0) to 393 K (x = 1.0). At 82 K, the saturation magnetization of all samples remains M <sub>S</sub> ≤ 3.5μ <sub>B</sub> /formula unit compared to a theoretical spin-only moment 4μ <sub>B</sub> /formula unit for a perfectly ordered compound. This discrepancy is probably due to a slight disorder and valence-fluctuation between the Fe and Mo atoms. © 2003 Elsevier Science B.V. All rights reserved.